Displaying 13 results of Tretinoin Impurities Tretinoin is a medication used to treat acne and other skin conditions. It is a potent derivative of vitamin A and works by increasing skin cell turnover, reducing inflammation and unclogging pores. However, as with any medication, there may be impurities present which can affect its effectiveness or cause adverse reactions. It is important to purchase tretinoin from a reputable source and follow the instructions of a healthcare professional.